The present invention is related to offshore oil well drilling platforms, and more specifically to a deep draft drilling platform in which a drilling rig is positioned below the surface of the water.
In well drilling operations, derricks are positioned over the well to provide a structure high above the well from which to suspend elongated sections of drilling pipe. In offshore drilling operations, it has become customary to provide large floating platforms on which such derricks or drilling rigs are positioned for well drilling operations. In addition, the required machinery, pumps, equipment, tanks, supplies, and personnel accommodations are also placed on the large floating drilling platforms. The floating platforms are usually positioned high above the surface of the water in order to place the derrick and such other equipment above surface wave action.
Although such conventional offshore drilling platforms have been used successfully to drill many offshore wells, the use of such platforms continues to present substantial safety problems. In particular, such floating drilling platforms with equipment and facilities supported high above the surface of the water, are unstable and dangerous in storm conditions and rough seas. Many lives have been lost as a result of such large floating drilling platforms capsizing and sinking in severe weather. Such conventional floating platforms are also dangerous when blowouts occur, since all of the personnel are confined to the area immediately adjacent the oil well where extreme fire and explosive conditions are particularly perilous and the ability to control such fires is inhibited by the ocean environment.